CC3351: hostapd Automatic Channel Selection(ACS) Hangs After Starting Scan (ACS-STARTED but Never Completes)

Tool/software:

Hello,

I am working with a Texas Instruments AM62-SIP board and am trying to enable Automatic Channel Selection (ACS) for a 5 GHz Access Point using hostapd.

The AP works perfectly when I set a static channel (e.g., channel=36). However, when I set channel=0 to enable ACS, the hostapd service starts the process but hangs indefinitely, and the AP's SSID is never broadcast.

Hardware and Software Details

• Board: TI AM62-SIP

• Wi-Fi module: cc3351

• Kernel: 6.6.58-k3

• Relevant hostapd.conf:

  Ini, TOML

  interface=wlan0
  driver=nl8211
  country_code=US
  ssid=TI-AP-BOARD3
  hw_mode=a
  channel=0 # Enable ACS
  ieee80211d=1
  ieee80211h=1
  ieee80211n=1
  ieee80211ac=1
  wpa=2
  wpa_passphrase=YourSecurePasswordHere
  wpa_key_mgmt=WPA-PSK
  

Debugging Steps Already Taken

1. Initially, the ACS scan failed because of a missing firmware file. The dmesg log showed:

   cc33xx_driver cc33xx.5.auto: Direct firmware load for ti-connectivity/cc33xx-nvs.bin failed with error -2
   

2. This has been RESOLVED. I have successfully placed the correct cc33xx-nvs.bin file in /lib/firmware/ti-connectivity/.

   1. curl -o ~/Downloads/cc33xx-nvs.bin https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/plain/ti-connectivity/cc33xx-nvs.bin
      

3. The dmesg log now confirms the driver is loading the file, with only a minor, non-fatal warning:

   cc33xx: WARNING NVS MAC address present but has a wrong size, ignoring.
   

4. The systemd service for hostapd has been configured to run it in the foreground to aid debugging.

Current Behavior (The Problem)

Even with the correct firmware in place, the ACS process starts but never finishes. After restarting the hostapd service, it remains stuck in an "activating" state for many minutes.

systemctl status hostapd.service shows the service is stuck starting:

● hostapd.service - Access point and authentication server for Wi-Fi and Ethernet
     Active: activating (start) since Thu 1970-01-01 00:40:41 UTC; 7min ago
...
Jan 01 00:40:43 am62xxsip-evm hostapd[67257]: ACS: Automatic channel selection started, this may take a bit
Jan 01 00:40:43 am62xxsip-evm hostapd[67257]: wlan0: ACS-STARTED

journalctl -eu hostapd.service confirms the ACS process starts, but it never logs a completion, failure, or chosen channel. It simply stops logging after ACS-STARTED.

iw dev wlan0 info shows the interface is in a hung state: it's in type AP mode, but no ssid or channel has been configured.

Interface wlan0
        ifindex 4
        wdev 0x1
        addr f8:fb:90:14:d9:a0
        type AP
        wiphy 0

My Question

Why does the hostapd ACS process hang indefinitely after starting the scan, even when the necessary firmware is present? Does the cc33xx driver on the AM62-SIP fully support the survey scan required by hostapd's ACS, or is this a known issue?

Any guidance would be greatly appreciated.

Thank you.